JP2006119082A - Steering angle detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering angle detecting device capable of detecting an absolute steering angle keeping a steering shaft stationary, and of detecting the steering angle, even in multiple rotations. <P>SOLUTION: The device comprises a main roller 2 with a radius R rotating in one body with a steering shaft 1, a first differential roller 3 with a radius r1 circumscribing the main roller 2, a second differential roller 4 with a radius r2 (r1<r2<R) circumscribing the main roller 2, a first rotation angle sensor 5 detecting the rotation angle θ1 of the first differential roller 3 within a range ±180°; a second rotation angle sensor 6 detecting the rotation angle θ2 of the second differential roller 4 within a range ±180°; and an arithmetic circuit calculating the steering angle Φ of the steering shaft 1, based on the phase difference α defined with two rotation angles θ1 and θ2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steering angle detection device that detects the absolute steering angle of a steering shaft that is rotated a plurality of times, and can detect an absolute steering angle while the steering shaft is stationary, and can detect a steering angle even in multiple rotations. About.

  2. Description of the Related Art As a steering angle detection device that detects the steering angle of a steering shaft of an automobile, one using an incremental optical encoder is known. This type of steering angle detection device detects the increase / decrease from the original steering angle by counting the number of pulse signals, and obtains the absolute steering angle by adding the increase / decrease to the original steering angle. . However, this type of steering angle detection device loses information on the original steering angle unless the power supply is always energized. For this reason, in the automobile, the battery power is consumed even in a situation where the detection of the steering angle is not necessary, and there is a possibility that the so-called battery rise may be caused.

  Further, since it is necessary to detect the steering angle as an angle corresponding to a plurality of rotations of the steering shaft, a rotation angle sensor for only one rotation is not sufficient. Therefore, two rotation angle sensors having different rotation ratios are used, and the steering angle is detected from the combination of the outputs of both rotation angle sensors. Among these types of steering angle detection devices, the steering angle detection device disclosed in Patent Document 1 can detect the absolute steering angle without moving the steering shaft. The main points of a conventional steering angle detection device using an absolute optical encoder and a magnetic rotation sensor will be described below.

  As shown in FIG. 7, the main sensor 101 includes an optical encoder plate 102 fitted on the steering shaft 6, and eight sets of light emitters and light receivers (collectively, arranged so as to sandwich the optical encoder plate 102). The optical sensor group 103 is an absolute type optical encoder. The optical encoder plate 102 is provided with a slit whose circumferential angle is represented by a code value composed of a gray code or a bit code. The optical encoder plate 102 rotates integrally with the steering shaft 6, whereas the optical sensor group 103 is fixed to the vehicle body. When the optical encoder plate 102 rotates, the light from the light emitter is received by the light receiver through the slit, and is not received when the light is blocked. By using eight sets of light emitters and light receivers, 360 ° can be expressed in 256 steps. If the steering shaft 6 rotates a plurality of times, the optical encoder plate 102 also rotates the same number of times. Therefore, the same reading value of the main sensor 101 is repeated every 360 °.

  The secondary sensor 104 incorporates a bar magnet 107 in a secondary gear 106 having a reduced number of teeth so as to increase the speed of the primary gear 105 fitted on the steering shaft 6, and the NS magnetic pole is connected to the secondary gear 106. A magnetic sensor (not shown) is made to face the auxiliary gear 106 in the axial direction so as to face the radial direction of the gear 106. The auxiliary sensor 104 repeats a waveform that changes sinusoidally with respect to the rotation angle of the auxiliary gear 106 every rotation of the auxiliary gear 106.

  The steering angle detection device described in paragraphs 0020 to 0052 of Patent Document 1 also substantially follows the configuration shown in FIG. In the case of Patent Document 1, 360 ° is expressed in 14 stages of C0 to C13. According to Patent Document 1, since the speed increasing ratio is 1.75 times, that is, the number of teeth of the main gear to the number of teeth of the sub gear is 7: 4, the main gear rotates four times (= the steering shaft is 4). Each time it rotates), the auxiliary gear rotates seven times.

  In the case of this steering angle detection device, there are a plurality of steering angles in which the combination of the rotation angle that can be read from the main sensor and the output voltage of the sub sensor is the same between the steering angles of the steering shaft from −720 ° to + 720 °. By taking into account the change state of the rotation angle that can be read from the main sensor and the change state of the output voltage of the sub sensor, it is possible to estimate the steering angle as one.

  In another form described from paragraph 0054 onwards of Patent Document 1, a potentiometer is used as the auxiliary sensor so that a waveform that linearly changes with respect to the rotation angle of the auxiliary gear is repeated for each rotation of the auxiliary gear. In this case, there are two steering angles in which the combination of the rotation angle read from the main sensor and the rotation angle read from the sub sensor is the same between the steering angles −720 ° to + 720 ° of the steering shaft. Therefore, the steering angle can be specified by the combination of the rotation angle that can be read from the main sensor and the rotation angle that can be read from the sub sensor.

JP 2002-98522 A

  Since the steering angle detection device using the incremental optical encoder needs to be energized at all times, power is wasted.

  In the steering angle detection device of Patent Document 1, since the main sensor is an optical encoder system, the resolution of the main sensor is as coarse as 25.7 °. The resolution of the steering angle is defined by the resolution of the main sensor.

  Further, in the steering angle detection device of the first form of Patent Document 1, there are a plurality of steering angles in which the combination of the rotation angle that can be read from the main sensor and the output voltage of the sub sensor is the same, and therefore the rotation that can be read from the main sensor. If the change state of the angle and the change state of the output voltage of the sub sensor are not taken into consideration, the steering angle cannot be reduced to one. That is, the steering angle cannot be detected while the steering shaft is stationary.

  On the other hand, the steering angle detection device of the second form of Patent Document 1 can detect the absolute steering angle while the steering shaft is stationary. However, since the gear ratio of the main gear and the sub gear is a simple integer ratio of 7: 4, when the main gear rotates four times (two rotations forward and backward), the sub gear rotates seven times and the rotation angle of both gears is 0 °. Since the output voltage of both sensors returns to the original combination, the steering angle is not fixed to one when the steering shaft exceeds four rotations, and the steering angle cannot be detected only by the rotation angles of the two sensors.

  Further, the steering angle detection device of Patent Document 1 and the one shown in FIG. 7 obtain the rotation of the sub sensor by engaging the sub gear 106 with the main gear 105 and transmitting the rotation. However, there is always play in the gears. Due to this backlash, the measurement accuracy of the steering angle cannot be improved. In addition, if tooth missing occurs in the main gear 105 or the sub gear 106, the sub sensor outputs an incorrect output, and the steering angle cannot be detected.

  Accordingly, an object of the present invention is to solve the above-described problems and provide a steering angle detection device that can detect an absolute steering angle while the steering shaft is stationary and can detect a steering angle even with multiple rotations. In addition to this purpose, it also has the purpose of solving the above-mentioned problems.

In order to achieve the above object, the present invention (Claim 1) includes a main roller that is fitted around a steering shaft and rotates integrally with the steering shaft and has a diameter R, and is rotated around the main roller. A first differential roller having a diameter r1 smaller than the diameter R of the main roller, and a diameter that is smaller than the diameter R of the first differential roller and is smaller than the diameter R of the first differential roller rotated circumscribed by the main roller. a second differential roller having r2, a first rotation angle sensor for detecting a rotation angle θ1 of the first differential roller in a range of ± 180 °, and a rotation angle θ2 of the second differential roller of ± 180 °. A second rotation angle sensor for detecting in the range of, and an arithmetic circuit for calculating the steering angle Φ of the steering shaft based on the phase difference α defined by the two detected rotation angles θ1, θ2.
The phase difference α is
When | θ1-θ2 | ≦ 180 °, α = θ1-θ2
When | θ1-θ2 |> 180 °,
If θ1 <0, α = θ1 + 360−θ2
If θ1> 0, α = θ1−360−θ2
Is defined by

Further, the present invention (Claim 2) includes a main roller having a diameter R that is fitted around a steering shaft and rotated integrally with the steering shaft, a belt that is circulated and driven by the main roller, and the belt. A first differential roller having a diameter r1 smaller than the diameter R of the main roller rotated in contact with the belt and a diameter r1 of the first differential roller rotated in contact with the belt and smaller than the diameter R of the main roller. A second differential roller having a large diameter r2, a first rotation angle sensor that detects a rotation angle θ1 of the first differential roller in a range of ± 180 °, and a rotation angle θ2 of the second differential roller is ± A second rotation angle sensor that detects within a range of 180 °; and an arithmetic circuit that calculates the steering angle Φ of the steering shaft based on the phase difference α defined by the two detected rotation angles θ1 and θ2. ,
The phase difference α is
When | θ1-θ2 | ≦ 180 °, α = θ1-θ2
When | θ1-θ2 |> 180 °,
If θ1 <0, α = θ1 + 360−θ2
If θ1> 0, α = θ1−360−θ2
Is defined by

  The arithmetic circuit calculates the steering angle Φ of the steering shaft by substituting the phase difference α into the steering angle arithmetic expression.

May be given in

  The arithmetic circuit may specify the steering angle Φ by applying the phase difference α to a steering angle versus phase difference characteristic stored in advance.

  A magnet is attached to each of the first and second differential rollers so that the magnetic poles are located across the center of the differential roller, and the magnetic sensor is opposed to each of the first and second differential rollers from the axial direction. The first and second rotation angle sensors may be configured.

  The present invention exhibits the following excellent effects.

  (1) The absolute steering angle can be detected while the steering shaft is stationary.

  (2) The steering angle can be detected even with multiple rotations.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the steering angle detecting device according to the present invention is fitted to a steering shaft 1 and rotates integrally with the steering shaft 1 to have a diameter R, and the main roller 2 includes A first differential roller 3 having a diameter r1 smaller than the diameter R of the roller 2 that is circumscribed and rotated, and a first differential roller 3 that is circumscribed to the main roller 2 and smaller than the diameter R of the main roller 2 is rotated. A second differential roller 4 having a diameter r2 larger than the first diameter r1, a first rotation angle sensor 5 for detecting a rotation angle θ1 of the first differential roller 3 in a range of ± 180 °, and a second differential roller 4 Of the steering shaft 1 based on the phase difference α defined by the two detected rotation angles θ 1 and θ 2. An arithmetic circuit (not shown) for calculating.

  The rotation angle sensor used for the first and second rotation angle sensors 5 and 6 may be anything as long as it outputs a signal proportional to the rotation angle, but here, the angle is measured without contact with the differential roller. A magnetic rotation angle sensor that can be detected is used. That is, the magnets 7 and 8 are attached to the first and second differential rollers 3 and 4 so that the magnetic poles are located on both sides of the center of the differential rollers 3 and 4, respectively. 4, the first and second rotation angle sensors 5 and 6 are configured such that the magnetic sensors 9 and 10 made of magnetoresistive elements face each other in the axial direction. The magnets 7 and 8 are circular magnets (also referred to as annular magnets) having N poles on one side and S poles on the opposite side with a diameter as a boundary. The magnets 7 and 8 are accommodated inside the first and second differential rollers 3 and 4 with the diameter centers of the magnets 7 and 8 aligned with the centers of the diameters of the first and second differential rollers 3 and 4. ing. Thereby, the N pole and the S pole are located on the opposite sides in the radial direction. The magnetic sensors 9 and 10 are disposed at the centers of the diameters of the first and second differential rollers 3 and 4 and are fixed to a non-rotating system (not shown).

  Since the rotation angle detection principles of the first and second rotation angle sensors 5 and 6 are the same, only the first rotation angle sensor 5 will be described. The magnetic flux sensing surface of the magnetic sensor 9 is directed in the axial direction of the first differential roller 3. When the magnetic flux from the N pole to the S pole of the magnet 7 passes through the magnetic flux sensing surface of the magnetic sensor 9, a voltage proportional to the magnetic flux is output from the magnetic sensor 9. The magnetic sensor 9 is an MR sensor for detecting a rotation angle, such as an MR sensor manufactured by Philips, and has two bridge circuits composed of MR elements arranged in a form shifted by 45 degrees. Thereby, outputs of a sin θ waveform and a cos θ waveform are obtained, and a signal obtained by obtaining atan θ (= sin θ / cos θ) from these two outputs is an output of the magnetic sensor 9.

  As shown in the figure, it is assumed that the N pole side of the magnet 7 is oriented in the direction of 0 ° (this is θ = 0), and the boundary line of the N pole S pole is oriented in the direction of ± 90 °. At this time, the voltage of the magnetic sensor 9 is zero. When the first differential roller 3 rotates, the magnet 7 rotates and the position of the N pole S pole changes, so that the magnetic flux passing through the magnetic flux sensing surface of the magnetic sensor 9 changes. Therefore, the voltage of the magnetic sensor 9 increases. Thereafter, when the first differential roller 3 is rotated to 90 °, the voltage of the magnetic sensor 9 is reversed from the maximum value to the minimum value. When rotated to 180 °, the S pole side of the magnet 7 faces the direction of 0 °, contrary to the illustration. At this time, the voltage of the magnetic sensor 9 becomes zero. When the first differential roller 3 further rotates, the voltage of the magnetic sensor 9 increases again and reverses from the maximum value to the minimum value at 270 °, and when the first differential roller 3 rotates 360 °, The voltage returns to the original zero. That is, two cycles of change occur within 360 ° rotation.

  No matter how many times the first differential roller 3 rotates beyond 360 °, the voltage change of the magnetic sensor 9 in one rotation follows the same course. Here, the rotation angle is represented by ± 180 ° with 0 ° as a reference. That is, if the first differential roller 3 is rotated by 200 °, the rotation angle at that time is expressed as −160 °. In other words, the magnetic sensor 9 outputs a voltage converted into a rotation angle of −160 °.

By changing the positional relationship between the magnet 7 and the magnetic sensor 9 described above, the voltage of the magnetic sensor 9 becomes 0 when the rotation angle is 0 °, and the magnetic sensor 9 is rotated from the rotation angle 0 ° to 180 ° in the positive direction. The voltage of the magnetic sensor 9 gradually increases with a positive value, and the voltage of the magnetic sensor 9 gradually decreases with a negative value until the rotation angle is rotated 180 ° in the negative direction from 0 °. Thus, the rotation angle and the sensor output voltage have a linear relationship, and the signs are also aligned. Hereinafter, it is considered that the voltage of the magnetic sensor 9 is equivalent to the rotation angle θ1 of the first differential roller 3 detected by the first rotation angle sensor 5.
When the main roller 2 rotates many times, the first and second differential rollers 3 and 4 rotate more than that. FIG. 2 shows changes in output of the first and second rotation angle sensors 5 and 6 due to this. The horizontal axis is the steering angle. The vertical axis represents the voltage of the magnetic sensors 9 and 10, but can be read as the rotation angles θ1 and θ2. For example, the voltage Vh can be read as the rotation angle + 180 ° and the voltage Vl can be read as −180 °. The broken line represents the output of the first rotation angle sensor 5, and the solid line represents the output of the second rotation angle sensor 6. The following will be described with reference to this figure.

  In the steering angle detection device of FIG. 1, when the main roller 2 rotates, for example, clockwise, the first and second differential rollers 3, 4 rotate counterclockwise. However, in the following, the direction in which the steering angle (= the rotation angle of the main roller 2 is represented by an angle range corresponding to a plurality of rotations) is increased (the normal rotation direction of the main roller 2) is the first and second differential rollers It is defined as 3 and 4 forward rotation directions.

  In this steering angle detection device, the rotation angles θ1, θ2 of the first and second differential rollers 3, 4 when the main roller 2 rotates by the steering angle Φ due to the difference in roller diameter (r1 <r2 <R). Is as shown in equations (1) and (2).

θ1 = Φ × R / r1 (1)
θ2 = Φ × R / r2 (2)
At this time, the rotation angles θ1 and θ2 are ± 180 ° or less (meaning that they do not exceed the range of ± 180 °, that is, −180 ° ≦ θ1, θ2 ≦ + 180 °), and therefore can be obtained by Expression (1). The range of the steering angle Φ or the range of the steering angle Φ that can be obtained by the equation (2) is limited to less than ± 180 ° (−180 ° <θ1, θ2 <+ 180 °).

Next, when the difference between Expression (1) and Expression (2) is obtained,
θ1-θ2 = Φ × R × (r2-r1) / (r1 × r2) (3)
It becomes. From this equation (3),

Is obtained. That is, the steering angle Φ can be calculated from the combination of the rotation angles θ1 and θ2. In this equation (4), if the diameter R of the main roller 2 is constant, the denominator is reduced by reducing the difference in diameter (r2-r1) between the first and second differential rollers 3, 4. The steering angle Φ increases. That is, even if the rotation angles θ1 and θ2 output from the first and second rotation angle sensors 5 and 6 are ± 180 ° or less, the steering angle Φ of ± 180 ° or more can be calculated.

  Next, the calculation method will be described.

  First, the phase difference α is defined as in the following equation (5).

α = θ1-θ2 (5)
When the main roller 2 rotates forward, the first differential roller 3 rotates faster than the second differential roller 4, so that when the rotation angle θ1 is 180 ° or less, θ1> θ2 and the phase difference α is positive. Value. However, at the moment when the first differential roller 3 further rotates and the rotation angle θ1 exceeds 180 °, the rotation angle θ1 discontinuously becomes −180 °. If this discontinuous point P is exceeded, the phase difference α cannot be defined by equation (5).

  In the state beyond the discontinuous point P, | θ1−θ2 |> 180 °. However, if 360 ° is added to the rotation angle θ1 at this time, an accurate value of the phase difference α can be obtained.

  Subsequently, when the rotation angle θ2 exceeds the discontinuous point Q, it returns to | θ1−θ2 | ≦ 180 °, so that it is not necessary to add 360 ° to the rotation angle θ1.

  On the other hand, when the main roller 2 rotates in the reverse normal direction, the first differential roller 3 also rotates faster than the second differential roller 4. However, since the sign of the rotation angle θ1 is negative, θ1 <θ2 and the phase difference α is a negative value. However, at the moment when the first differential roller 3 further rotates and the rotation angle θ1 exceeds −180 °, the rotation angle θ1 becomes discontinuously 180 °. If this discontinuous point R is exceeded, the phase difference α cannot be defined by equation (5).

  Again, in the state beyond the discontinuity point R, | θ1−θ2 |> 180 °. However, if 360 ° is subtracted from the rotation angle θ1 at this time, an accurate value of the phase difference α can be obtained.

  Subsequently, when the rotation angle θ2 exceeds the discontinuous point S, it returns to | θ1−θ2 | ≦ 180 °, so that it is not necessary to add 360 ° to the rotation angle θ1.

In summary, if | θ1−θ2 | ≦ 180 °, the phase difference α may be defined by Equation (5). When | θ1-θ2 |> 180 °, an addition or subtraction term of 360 ° may be added to Equation (5). Whether 360 ° is added or subtracted can be determined by the sign of the rotation angle θ1. Therefore,
If θ1 <0, α = θ1 + 360−θ2 (5 ′)
If θ1> 0, α = θ1−360−θ2 (5 ″)
Can be defined.

  As described above, the phase difference α can be defined for all combinations of the rotation angles θ1 and θ2. Also, the equation (4) is

Can be expressed as This formula (6) is called a steering angle calculation formula. The steering angle Φ can be obtained by substituting the phase difference α into the steering angle calculation formula (6). FIG. 2 shows which equation (5), (5 ′), (5 ″) represents the phase difference α.

  FIG. 3 shows the steering angle versus phase difference characteristics. As shown in the figure, the phase difference α = 0 when the steering angle Φ = 0 °, and the phase difference α changes linearly from the steering angle Φ = −1080 ° to + 1080 °.

  Instead of substituting the phase difference α into the steering angle calculation formula (6), the arithmetic circuit stores the steering angle vs. phase difference characteristic of FIG. 3 in a table in advance, and the phase difference α is added to this steering angle vs. phase difference characteristic. Can be applied to specify the steering angle Φ.

Incidentally, in the steering angle calculation formula (6), if the absolute value of the phase difference α is less than 180 °, the steering angle Φ can be calculated. If the rotation speed of the steering shaft 1 is n, the steering angle Φ can be calculated up to n × 360 °.
R × (r2−r1) (n × 360 °) / (r1 × r2) <180 °
If it is.

Than this,
2R * (r2-r1) * n <r1 * r2 (7)
And the equation for n,
n <(r1 * r2) / {2R * (r2-r1)} (8)
Is obtained.

For example, when R = 25 mm, r2 = 13 mm, r1 = 12 mm,
n <3.12
Therefore, the steering angle Φ for ± 3 rotations can be calculated.

  Since the steering angle detection device of the present invention calculates the steering angle Φ based on the phase difference α between the two differential rollers, the absolute steering angle can be detected while the steering shaft is stationary, and the power is turned on. Detection can be performed immediately from the point of time.

  Since the phase difference α is defined according to the rotation angles θ1 and θ2 of the two differential rollers 3 and 4, the steering angle can be detected even with multiple rotations.

  Further, since the steering angle detection device of the present invention does not use gears and uses rollers, there is no backlash and the measurement accuracy of the steering angle is improved. In addition, there is no problem due to missing teeth.

  Next, an embodiment in which the steering angle detection device of the present invention is mounted on a vehicle will be described.

  As shown in FIG. 4, the vehicle is provided with a rack 41 and a pinion 42 in combination, and tires 44 are attached to both ends of the rack 41 via joints 43 so as to be rotatable in the horizontal direction. On the other hand, the steering shaft 1 is connected to the pinion 42 via a joint 45. When the steering shaft 1 is rotated by the steering handle 48, the rack 41 moves linearly to change the direction of the two tires 44.

  The steering shaft 1 is provided with the steering angle detection device of the present invention. The outputs of the first and second rotation angle sensors 5 and 6 in the steering angle detection device are input to the calculation processor 46 that performs the calculation of the steering angle detection described above, and the steering angle output by the calculation processor 46. Information is transmitted to the upper motion controller 47.

  When the motion controller 47 has an automatic steering function, for example, the steering angle information output from the arithmetic processor 46 can be used. Furthermore, the steering angle information output from the arithmetic processor 46 can also be used when the motion control controller 47 performs the self-contained navigation according to the map information from the car navigation system.

  As shown in FIG. 5, the steering angle detection device of the present invention has a casing 51 provided so as to surround the steering shaft 1 and fixed to the vehicle body, and the main roller already described in the casing 51. Constituent members such as 2, first and second differential rollers 3 and 4 are accommodated. The main roller 2 is fixed to the steering shaft 1 and rotates integrally with the steering shaft 1. The first and second differential rollers 3 and 4 are configured so that a roller shaft (not shown) is supported by the casing 51 and rotates along with the main gear 5.

  Further, in this embodiment, a substrate 52 is provided in the casing 51, and the magnetic sensors 9 and 10 as the first and second rotation angle sensors 5 and 6 and the arithmetic processor 46 are mounted on the substrate 52. ing. As described above, since the electric system members of the magnetic sensors 9 and 10 and the arithmetic processor 46 are mounted on the same substrate 52, the space occupied by the steering angle detection device can be reduced.

  In the embodiment of FIG. 1, the first and second differential rollers 3 and 4 are rotated by obtaining a rotational force from the main roller 2 by contacting the main roller 2. However, the method for transmitting the rotational force is not limited to this. In the form shown in FIG. 6, a belt 61 is hung on the main roller 2, and the belt 61 is circulated and driven by the rotation of the main roller 2. The first and second differential rollers 3 and 4 are not in contact with the main roller 2 but are in contact with the belt 61. Accordingly, when the main roller 2 rotates clockwise, the first and second differential rollers 3 and 4 also rotate clockwise. The direction of rotation of the first and second differential rollers 3 and 4 is opposite to that of the configuration in FIG. 1, but the direction in which the steering angle increases positively is defined as the forward rotation direction of the first and second differential rollers 3 and 4. If there is no problem, the steering angle Φ can be calculated by substituting the phase difference α described so far into the steering angle calculation formula (6).

It is sectional drawing of the steering angle detection apparatus which shows one Embodiment of this invention. It is a steering angle vs. voltage characteristic diagram of the rotation angle sensor in the present invention. It is a steering angle versus phase difference characteristic diagram in the present invention. 1 is a steering structure diagram of a vehicle equipped with a steering angle detection device of the present invention. FIG. 5 is a cross-sectional view of the internal structure of the steering angle detection device of FIG. 4. It is sectional drawing of the steering angle detection apparatus which shows one Embodiment of this invention. It is a top view of the conventional steering angle detection apparatus.

Explanation of symbols

1 steering shaft 2 main roller 3 first differential roller 4 second differential roller 5 first rotation angle sensor 6 second rotation angle sensor 7, 8 magnet 9, 10 magnetic sensor

Claims (5)

A main roller having a diameter R that is externally fitted to the steering shaft and rotated integrally with the steering shaft, and a first difference that has a diameter r1 that is circumscribed by the main roller and rotated smaller than the diameter R of the main roller. A moving roller, a second differential roller that is rotated circumscribing the main roller and has a diameter r2 that is smaller than the diameter R of the main roller and larger than the diameter r1 of the first differential roller, and the first differential roller A first rotation angle sensor for detecting a rotation angle θ1 of the second differential roller in a range of ± 180 °, a second rotation angle sensor for detecting a rotation angle θ2 of the second differential roller in a range of ± 180 °, and the detected An arithmetic circuit for calculating a steering angle Φ of the steering shaft based on a phase difference α defined by two rotation angles θ1 and θ2.
The phase difference α is
When | θ1-θ2 | ≦ 180 °, α = θ1-θ2
When | θ1-θ2 |> 180 °,
If θ1 <0, α = θ1 + 360−θ2
If θ1> 0, α = θ1−360−θ2
A steering angle detection device defined by A main roller having a diameter R that is externally fitted to the steering shaft and rotated integrally with the steering shaft, a belt that is circulated and driven by the main roller, and a diameter R of the main roller that is rotated in contact with the belt A first differential roller having a smaller diameter r1, and a second differential roller rotated in contact with the belt and having a diameter r2 smaller than the diameter R of the main roller and larger than the diameter r1 of the first differential roller; A first rotation angle sensor that detects a rotation angle θ1 of the first differential roller in a range of ± 180 °, and a second rotation angle that detects a rotation angle θ2 of the second differential roller in a range of ± 180 °. A sensor and an arithmetic circuit for calculating a steering angle Φ of the steering shaft based on a phase difference α defined by the detected two rotation angles θ1 and θ2.
The phase difference α is
When | θ1-θ2 | ≦ 180 °, α = θ1-θ2
When | θ1-θ2 |> 180 °,
If θ1 <0, α = θ1 + 360−θ2
If θ1> 0, α = θ1−360−θ2
A steering angle detection device defined by The arithmetic circuit calculates the steering angle Φ of the steering shaft by substituting the phase difference α into the steering angle arithmetic expression.

The steering angle detection device according to claim 1, wherein the steering angle detection device is given by:   3. The steering angle detection device according to claim 1, wherein the arithmetic circuit specifies the steering angle Φ by applying the phase difference α to a steering angle versus phase difference characteristic stored in advance.   A magnet is attached to each of the first and second differential rollers so that the magnetic poles are located across the center of the differential roller, and the magnetic sensor is opposed to each of the first and second differential rollers from the axial direction. The steering angle detection device according to any one of claims 1 to 4, wherein the first and second rotation angle sensors are configured.

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